There was a discussion on one of the FB groups about intermediate block signals. Whilst these were a feature on BR lines where LT trains worked over, I can only think of 2 instances of intermediate blocks, both on the District. One was Revelstoke road between Southfields and Wimbledon Park, the other was between Kew Gardens and Richmond. Were there any others on other bits of "joint running"? Were they a feature on LT lines before the advent of widespread colour light signalling?